Data Emperor Chen Qin
Parents' age and whether their children are excellent or not should actually be discussed in two stages. The first stage is 10 pregnancy. In this regard, many of the previous answers have been completely said, including the increase in the difficulty of pregnancy, the increase in abortion rate, the increase in the probability of Down syndrome and so on. It should be said that elderly parents, especially elderly mothers, are more bumpy and face greater risks in the whole process of pregnancy and childbirth.
But for a child's life, ten months in the mother's womb is just a fragment. What will a pair of young parents in their early twenties and another pair of mature parents in their thirties bring to their children? What we are going to discuss here is what will happen after the baby is born.
weight
It is generally believed that the newborn's weight has an inverted U-shaped relationship with the mother's age, that is, with the increase of the mother's age, the newborn's weight first rises and then falls, and this inflection point generally appears between 30 and 35 years old. In other words, if you have another child after the age of 30, the child's constitution may be even greater. However, as can be seen from the figure below, this effect is not particularly obvious. Children born to mothers of all ages weigh the same at birth.
Some friends may think that the newborn's weight is only one aspect, which is not necessarily a good thing, not to mention that heavier newborns may need caesarean section. However, in fact, we can find that the phenomenon that the maternal child is overweight at the age of 30-35 not only appears at birth, but also persists after the child grows up, and the degree is even greater than that at birth. The following figure shows that if the weights of children aged 7-8 are compared, the children whose mothers are 33 years old (54.7 kg) are 65,438+03 kg heavier than those whose mothers are only 65,438+06 years old (465,438+0.7 kg). With the further improvement of the mother's childbearing age, when the childbearing age reaches 38, the weight of children aged 7-8 will return to about 40 kg.
We may still have questions about this:
First of all, is it good to be heavier? This is a matter of opinion, but for most children, underweight is often closely related to "weakness".
Secondly, is the difference in children's weight determined by "newborn physique" or by the process of raising? On the variable of weight, it is difficult to separate the congenital and acquired influences, but separating these two influences will not help us much-because this data model itself is interesting enough. Even if the research finds that the parenting process has a great influence on the child's weight, it is difficult for us to let a 16-year-old mother raise her child in the way of a 33-year-old mother.
height
Perhaps "heavier" is not a very positive word, but "higher" is obviously what parents are pursuing now. Height is a variable greatly influenced by parents' height (genetic influence) and children's age. Therefore, if we only average the height of children, we may get a mixed data of the age effect of children and the height effect of parents. We treat the variable height as follows:
First, subtract the average height of the child from the height of the child of the same age, that is, calculate how many centimeters the child is taller/lower than the child of the same age.
Secondly, use the height of the child's parents to return the deviation of the height value of each age group.
Finally, the residual that can't be explained by parents' height in the second step regression is obtained.
At this time, this residual is a numerical value that removes the age effect and parental gene effect, and only contains two parts of information: "the constitution of the newborn" and the process of parenting.
The picture above lists the relationship between the child's height and the mother's childbearing age. When fitting, we can easily find that there is also an inverted U-shaped relationship, that is, with the increase of the mother's childbearing age, the child's height first increases and then decreases (although there are more average data after the age of 37, the number of samples is small, which has no effect on the entire inverted U-shaped). Using quadratic fitting, we can find the peak of height-when the mother chooses to give birth at the age of 33, the height of the child is the highest; Children born at or before the age of 23 are about 1 to 5 cm lower than their peers. Maybe it's because of poor physical condition, maybe it's because of some problems in postpartum care, but whatever the reason, it's a statistically significant fact that children born before the age of 23 are shorter than their peers.
health
Children born to mothers aged 30-35 are not only heavier at birth, but also taller and heavier when they grow up to 7-8 years old; Children born before the age of 23 are at a disadvantage in height and weight. One possible reason is that the latter is physically weak. Using the variable "how many times did the child go to the hospital before he was one year old" can measure the child's congenital physical condition to some extent.
Results As expected, the frequency of medical visits before 1 year showed a positive U-shape with the increase of mother's age, which first decreased and then increased. After using quadratic fitting, we found that the lowest number of medical visits occurred at the age of 365,438+0. The data shows that children born between the ages of 27 and 32 have relatively low number of medical visits before their first birthday, so they are healthier.
Education level and short-term memory
From the previous analysis, we can draw a relatively stable conclusion-children born at the age of 30-35, whether congenital or acquired, are stronger and taller. But will there be a phenomenon of "developed limbs and simple mind"? We can start with the variable of years of education. Like the analysis of height, we first subtract the average years of education from each age group to figure out how many grades the children are higher/lower than their peers, and then explain the years of education higher/lower than their peers by the education level of their parents. Then the unexplained part is considered to be caused only by the innate and acquired factors brought by the mother's childbearing age, and has nothing to do with other genes and other factors.
The above picture shows that although the limbs are developed, the mind is not simple. Children born to mothers aged 30-32 are about 0. 1 level higher than their peers.
The same pattern also appears in short-term memory.
Short-term memory is tested in the survey as follows: the investigator reported 10 words, the respondent remembered them in two minutes, and then repeated them in two minutes. It can be seen that children whose mothers are 26-35 years old have better short-term memory than their peers, and the 33-year-old mother performs best.
conclusion
From the perspective of increasing the probability of birth defects, it seems useless to postpone childbirth. But the child's life is not just ten months in the mother's womb.
According to the above analysis, we can see that when the mother's childbearing age is in the range of 30-35 years old, the child is in the range of 0- 15 years old, and all aspects of performance are better. Although there are many acquired factors here (mothers in their thirties are better at taking care of their children and have more financial strength to ensure their nutrition and education), can we completely deny the existence of congenital factors? I'm afraid it still won't work. Choosing to have children after the age of 30 may have biological benefits in addition to sociological benefits, although I don't know what these benefits may be.
Finally, I hope young women can resist all kinds of pressures from society and friends and stick to their choices. There are gains and losses in having children at any time. When you and your family are more mature, having children is not so terrible, and there may be many additional benefits.
note:
1, all data are from CFPS20 12.
2. This paper is not an academic paper, so in order to make the chart more visual impact, the upper and lower limits of each icon have been artificially screened by me, but the measurement results are very significant.
3. There is no fixed pattern of the influence of father's childbearing age on children, so this paper does not analyze it. Except for one case: the later the father gives birth, the lower the height of the child-because the average age of shorter men getting married and giving birth is later.